1. Field of the Invention
The present invention relates to an image display apparatus and an image display method for displaying a still image.
2. Description of the Related Art
In a case where the aspect ratio of an image to be displayed on an image display apparatus (hereinafter referred to as an “original image”) is different from that of a display area of the image display apparatus, an image displayed on the display area (hereinafter referred to as a “display image”) may be poorly viewed when an attempt is made to display the entire original image on the display area. This is because the original image needs to be resized in accordance with the size in either the vertical direction or the horizontal direction of the display area and the display image cannot be displayed on the entire display area.
If the entire original image is to be displayed when the value from ((the number of pixels in the horizontal direction)/(the number of pixels in the vertical direction)) of the original image is smaller than the value from ((the number of pixels in the horizontal direction)/(the number of pixels in the vertical direction)), the original image needs to be resized so that the vertical direction of the display image matches the vertical direction of the display area. As a result, a blank area appears at least either the left or right side of the display image.
Japanese Patent Laid-Open No. 3-46073 discloses a technique relating to the problem discussed above. Specifically, if a vertically oriented (i.e. vertically long) original image is displayed on a horizontally oriented (i.e. horizontally long) high-vision monitor, the original image is rotated 90 degrees (laid) and recorded in a frame memory. Then the vertically oriented portion of the image (16:9 vertical to horizontal) is cut out. Then the cut out image is rotated 90 degrees in the reverse direction (raised), transferred to a display memory and resized so that the size of the display image in the horizontal direction matches the size of the display area in the horizontal direction. As a result, the display image can be displayed in the entire display area: however, this alone does not allow a user to view the entire original image. Therefore, the process of sequentially shifting to the right or left an image area cut out from the frame memory is repeated so that the display image is scrolled in the vertical direction thereby the user can view the entire original image.
The method of Japanese Patent Laid-Open No. 3-46073 only takes account of the case where a vertically oriented original image is displayed on a high-vision monitor, i.e., where the value from ((the number of pixels in the horizontal direction)/(the number of pixels in the vertical direction)) of the original image is smaller than the value from ((the number of pixels in the horizontal direction)/(the number of pixels in the vertical direction)) of the display area. The method of Japanese Patent Laid-Open No. 3-46073 records the original image in a frame memory of the high-vision monitor in the size of 1920 pixels in the horizontal direction and 1035 pixels in the vertical direction. Thus, whether the original image is vertically oriented or horizontally oriented, easily-viewable display from original images with aspect ratios other than 16:9 horizontal to vertical (9:16 horizontal to vertical in the vertically oriented case) has not been considered. In addition, the method of Japanese Patent Laid-Open No. 3-46073 does not take account of intentionally displaying the entire original image on a display area even when the aspect ratio of the display area of the image display apparatus is different from the aspect ratio of the original image.
As the original image, however, may actually be vertically oriented or horizontally oriented and the aspect ratio varies, the method of Japanese Patent Laid-Open No. 3-46073 cannot generate an easily-viewable display image from such an original image. In addition, depending on a purpose of displaying an image, scrolling the display image may be undesirable even when the aspect ratio of the original image is different from that of the display area. The method of Japanese Patent Laid-Open No. 3-46073, however, cannot deal with such a case.
The present invention has been made in view of such circumstances, and provides a technique for generating a display image with high viewability to a user even from an original image with any aspect ratio. The invention also provides a technique for generating a display image taking account of the fact that an easily-viewable display image for a user may vary depending on a purpose of displaying the image.